The British patent GB 1 533 235 discloses antipsychotically effective thienobenzodiazepines by a generic formula which also covers olanzapine.
U.S. Pat. No. 5,229,382 describes olanzapine explicitly. The described process for its production involves a crystallization from acetonitrile, determining the melting point of that crystallized compound at 195° C.
EP-B-733 635 claims crystalline form II olanzapine and this polymorphic form is said to be more stable than the material obtained according to U.S. Pat. No. 5,229,382 which is designated “form I olanzapine”. Both the form I and the form II of olanzapine are characterized by e.g. x-ray data. The preparation of the more stable form II of olanzapine is effected by dissolving technical grade olanzapine in ethyl acetate and crystallization from the resulting solution by any conventional process such as seeding, cooling, scratching the glass of the reaction vessel or other common techniques.
WO 02/18390 discloses the monohydrate form I and the dihydrate form I of olanzapine, a process for production thereof and a process for production of form I of olanzapine which comprises the steps of stirring olanzapine monohydrate form I or crude olanzapine or form II of olanzapine in methylene chloride at reflux, cooling, filtering and drying. It is also described that a repeating of the process described in U.S. Pat. No. 5,229,382 Example 1, subexample 4 did not lead to formation of form I of olanzapine.
EP-B-733 634 relates to three specific solvates of olanzapine namely the methanol, ethanol and 1-propanol solvates and a process for production technical grade olanzapine by drying the corresponding solvate.
EP-B-831 098 relates to processes for preparation of form II of olanzapine by drying olanzapine dihydrate intermediates in a vacuum oven.
EP-A-831 097 relates to olanzapine dihydrate D.
In WO 01/47933 three new polymorphic forms designated as form III, IV and V and methods for preparing them are disclosed. The processes involve a dissolving of form I or form II of olanzapine in aqueous organic or anorganic acid and precipitating the desired material by neutralisation.
US patent application 20020086993 discloses new polymorphic form designated as form X of olanzapine and a method for its preparation.